1. Field of the Invention
The present invention relates to a light source unit which is able to diffuse a laser beam sufficiently, a projector which includes this light source unit, and an image projection method.
2. Description of the Related Art
In these days, data projectors are used on many occasions as an image projection unit which projects images including an image of a screen and a video image of a personal computer, as well as images based on image data which is stored on a memory card on to a screen. In these data projectors, light emitted from a light source is caused to converge to a micromirror display element called a DMD (Digital Micromirror Device) or a liquid crystal panel so that a color image is displayed on a screen.
Conventionally, the mainstream of these projectors has been those which utilize a high-intensity discharge lamp as a light source. In recent years, however, there have been made many developments on projectors which use, as a light source, a light emitting diode, a laser diode, an organic electroluminescence, a luminescent material or the like.
Japanese Unexamined Patent Application (KOKAI) No. 2008-122823 (JP-2008-122823 A) discloses, as a projector which can project a highly bright image, a projector which uses a laser beam emitting device as a light source so that projection image light which is modulated by an image signal is formed by a laser beam which is emitted from the laser beam emitting device. Additionally, in this projector, in emitting projection image light formed by the laser beam, the projection image light is caused to pass through a movable diffusing portion so as to remove speckle noise generated in a projection image formed by the coherent laser beam.
In the projector as described above, the projection image light which is formed by modulating a coherent laser beam by the image signal is caused to pass through the movable diffusing portion in order to reduce or remove the speckle noise, thus the speckle noise in the projection image formed by the laser beam is reduced or removed, however there may be a case where the speckle noise remains in the projection image.